Australia's floods, cyclone stress Barrier Reef

FILE - In this Nov. 2002 file photo provided by Queensland Tourism, an unidentified woman snorkels on the Great Barrier Reef off Australia's Queensland state. Researchers said it is too early to know exactly how much of the reef has been affected by recent flooding, which carved a wide path of destruction on land before draining into the sea off the country's northeast coast. (AP Photo/Queensland Tourism, File) EDITORIAL USE ONLY
— AP

FILE - In this Nov. 2002 file photo provided by Queensland Tourism, an unidentified woman snorkels on the Great Barrier Reef off Australia's Queensland state. Researchers said it is too early to know exactly how much of the reef has been affected by recent flooding, which carved a wide path of destruction on land before draining into the sea off the country's northeast coast. (AP Photo/Queensland Tourism, File) EDITORIAL USE ONLY
/ AP

Coral ecologist Alison Jones has been examining several reefs in the Keppel Islands, an area in the reef's southern tail where floodwaters spilled into the sea, and found isolated damage to coral in waters less than 6 1/2 feet (2 meters) deep.

"I wouldn't like there to be another flood because they're certainly pale, they've obviously been starved of light for a few weeks," she said. "But they're doing remarkably well below 2 meters, so that's an enormous relief to me."

She cautioned that her observations were preliminary and limited to one small segment of the reef.

Katharina Fabricius, principal research scientist at the Australian Institute of Marine Science, said the severe flooding seen in the Queensland capital of Brisbane was too far south to have affected the reef. But rivers farther north are still carrying water loaded with high levels of nutrients and sediment, which is worrying, Fabricius said.

She said she is more concerned about the cumulative effects of several severe storms and floods in recent years. Five Category 4 or Category 5 cyclones - the two most powerful storm classifications - have roared over the reef in the past six years, while there were only two of that ferocity in the 40 years before that, she said.

"We don't fully understand what happens when a reef is hit by so many types of disturbances so often," she said. "The reefs just don't get enough time to recover from one disturbance before they're hit again."

Scientists predict that extreme weather events will increase in both intensity and frequency due to global warming.